Printing plate saddle with living hinge

ABSTRACT

A lightweight plastic saddle for mounting of thin shell printing plates is provided. The body of the saddle is provided with waffle ridging consisting of longitudinal runners and angled cross ribs to reinforce the curved body. The ribs are angled progressively greater toward the ends to provide the necessary draft when the saddle is removed from the forming mold, but without sacrificing reinforcement of the supporting runners when the saddle is mounted on a printing cylinder. The runners are provided with an interruption and the body with a rounded groove at the center of the saddle to form a living hinge across the saddle to permit initial mounting, stretching and holding of the plate and easy installation on the cylinder.

[451 July 17,1973

[ PRINTING PLATE SADDLE WITH LIVING 2,086,145 7/1937 101/378 2,630,756 3/1953 Crabtree et 101/378 HINGE [76] Inventors: Stanley W. MacDonald; George Primary Examiner clyde L Coughenour Mottl, both of 402 South Cass Atmmey LOWe and King Avenue, Westmont, 111. 60599 Mar. 7, 1972 [57] ABSTRACT A lightweight plastic saddle for mounting of thin shell [22] Filed:

Appl. No.: 232,422

printing plates is provided. The body of the saddle is provided with waffle ridging consisting of longitudinal runners and angled cross ribs to reinforce the curved body. The ribs are angled progressively greater toward the ends to provide the necessary draft when the saddle is removed from the forming mold, but without sacrificing reinforcement of the supporting runners when the 665 7 o wa 2 41i 41.6 Mm 4 W3 .15 00 mice mnfi "3 "4 n ""5 Th2 MR NW3 1 0 6 .12 mu IF 1.] 8 55 [.1

saddle is mounted on a printing cylinder. The runners are provided with an interruption and the body with a rounded groove at the center of the saddle to form a living hinge across the saddle to permit initial mounting, stretching and holding of the plate and easy installation on the cylinder.

[56] References Cited UNITED STATES PATENTS 101/395 8 Claims, 5 Drawing Figures 2,474,889 7/1949 Crafts 2,966,848 1/1961 Faeber 1,830,584 11/1931 Wood 2,261,305 11/1941 Stephenson.....

3,216,353 1 1/1965 Wallenius PRINTING PLATE SADDLE WITH LIVING HINGE The present invention relates to printing, and more particularly, to the mounting of thin shell plates on a rotary printing cylinder.

BACKGROUND OF THE INVENTION Today, in the stereographic and letter press printing press, it is normal practice to employ a thin shell metal plate mounted on a support saddle in lieu of the prior art cast metal plate. The thin shell plate and saddle combination offers several advantages in terms of a lighter weight printing surface, the ability to reuse the base or saddle during sveral printing runs and the ability to use the low-cost printing shells rather than the previously used lead plates. Several attempts have been made during recent years, such as shown by Wirth, US. Pat. No. 2,970,540 issued Feb. 7, 1961, to improve the printing plate saddles to make the thin shell plate and saddle combination even more economical and desirable. Such attempts have been qualified successes, but in addition to the need for still lower cost and lighter weight, it is generally accepted by those in the art that areas of needed improvement that still exist today are: (l capability to hold the thin-shell plate in initial position on the saddle prior to clamp down; (2) more easily clamped onto a printing cylinder; (3) stronger so as to resist the clamping forces and the centrifugal forces generated by the turning of the cylinder; (4) sufficiently free of fatigue weakening to be reuseable during at least 100 printing applications; (5) tighter adherence to the surface of the printing cylinder; and (6) more economical and servicable center hinge structure.

OBJECTIVES OF THE INVENTION Thus, it is one object of the present invention to provide a printing plate saddle that is lightweight, economical to construct and yet strong to take the forces acting thereon, and more specifically, to meet the areas of needed improvement mentioned above.

It is another object of the present invention to provide a printing plate saddle provided with waffle ridging on the back to minimize the amount of material used and to increase the strength of the saddle.

It is still another object of the present invention to provide a saddle having a living hinge at the midpoint to allow flexure of the saddle to easily receive the thin shell plate, andv then automatically return to substan tially semicircular configuration to stretch and maintain the plate in position prior to clamp down on the cylinder.

BRIEF DESCRIPTION OF THE INVENTION A saddle for a printing plate is provided which is molded from a high strength, lightweight plastic, such as nylon. The saddle includes a curved body having a smooth curved surface upon which to mount a thin shell printing plate. The body of the saddle includes novel waffle ridging on the rear face that adds the requisite strength to the saddle but minimizes the weight of the saddle by virtue of the voids formed between the ridging. The longitudinal runners of the ridging engage the surface of the cylinder and hold the saddle against longitudinal, aswell as lateral, shifting when the clamping pressure is applied at the ends of the saddle. The holding forces are greater than in prior art solid molded saddles since the total area of engagement is greatly reduced and the resilient, plastic runners thus have a tendency to have a greater bite" onto the surface.

Cross ribs are provided between the runners to add reinforcement to the saddle. The ribs vary in angle to ward an acute angle adjacent the ends of the saddle to provide mold draft in order that the saddle may be easily withdrawn after forming. The progressively increasing angling of the cross ribs toward the ends of the saddle has been discovered not to lessen the reinforcement capability and gives increased resiliency of the runners at the ends.

The end edges of the thin shell plate are connected to suitable fastener means on the runner extensions at the ends of the saddle. Between the runners and the extensions at each end, a transverse groove for receiving the locking clamps is provided.

Another feature of the invention is concerned with the hinge, preferably at the midpoint of the saddle, that allows the thin shell plate to be conveniently mounted on said saddle prior to clamp down of the combination on the printing cylinder. The hinge is advantageously formed as a living hinge by a cutout portion or interruption of the longitudinal ribs of the waffle ridging and a corresponding transverse groove on the underside of the body. Because of the inherent elastic nature of the plastic, the saddle may be flexed along the center line as desired to allow attaching the ends of the plate to the extensions. Releasing the force causing the flexure, advantageously returns the saddle to the curved configuration to stretch the thin shell plate and thereby prevent deleterious wrinkling of the thin shell plate before or during installation and clamp down on the face of the printing cylinder.

Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein we have shown and described only the preferred embodiment of the invention, simply by way .of illustration of the best mode contemplated by us of carrying out our invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modification in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regardedas illustrative in nature, and not as restrictlVe.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows the general features of the saddle of the present invention;

FIG. 2 is aside view of the saddle partially in cross DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the figures, the detailed description of the preferred embodiment of the invention will now be undertaken. Referring to FIGS. 1 and 2, the invention may broadly be described as a saddle, which is generally denoted by the numeral 10, for the mounting of a thin-shelled printing plate, such as P. The saddle 10 is constructed of a lightweight plastic material, such as nylon. This particular plastic material, although others could be substituted, provides strength and resiliency thereby allowing the saddle to resist clamping forces and flex during printing while preventing fatigue weakening during extended use.

The saddle 10 is broadly shown in FIG. 1 and in more detail in FIGS. 2-5. In FIG. 1, the saddle is seen to comprise a body 11 which comprises a smooth top surface 12 for mounting the plate I, a ridged rear or underside surface, generally denoted by the numeral 13, a transverse groove generally shown by numeral 14, and a plate locking means 15. A hinge, generally denoted in FIG. I by the numeral 16, provides a means of flexing the saddle from the dashed line position to the full line position detail below.

In FIG. 2, the saddle is shown positioned on a cylindrical mounting member, such as M. The mounting member could be a variety of forms and the cylindrical shape shown in FIG. 2 is understood to be used only as an example.

As seen in FIG. 2, the underside surface 13 comprises a plurality of cross ribs 20 which do not all contact the surface of the member M. The ribs are transversely disposed between longitudinal runners 21. The longitudinal runners are best shown in FIG. 4 and will be further discussed below.

The ribs 20 are inclined toward the underside surface 13 to form an angle with the underside surface. The angle 0 varies from almost perpendicular adjacent the hinge 16 to an acute angle near the ends of saddle 10. Varying the angle 0 is a means of providing a draft for removing the saddle from a forming mold. As can be seen in FIG. 2, the ribs are all essentially of equal length. Thus, varying angle 0 allows the end located ribs to provide reinforcement equal to that provided by the centrally located ribs without interfering with the aforementioned draft means.

Varying angle 0 also provides a further function by allowing a predetermined amount of deformation of runner 21 when the saddle is clamped onto member M, as will be discussed more in detail later. Clamps C, shown in FIGS. 2 and 5, impart a holding force to the saddle by means of tensile forces transmitted through the transverse groove 14 to the. longitudinal runners 21. This tensile force is not diminished by any components of said holding force and thus is a very effective means of holding the saddle in position.

Referring now to FIG. 4, it is seen that rear surface 13 comprises a plurality of longitudinal runners 21 of essentially equidistant spacing across the saddle. The runners comprise engaging face 22 which contacts the surface of mounting member M. Engaging face 22 contains the minimum surface area of the runners 21. Pressure resulting from the holding forces exerted by the clamps C is therefore maximized due tothis minimum area of contact. As mentioned above, all of the ribs do not contact the surface of the mounting member. Some of the runners 21, however, are allowed to contact the surface of member M when said holding forces are applied, as will be discussed below in connection with the more specific discussion of the angular positioning of said ribs.

By referring to FIG. 4, the function of the variation of angle 0 of the cross ribs on the underside of the saddle may now be discussed. The cross rib 20 shown in FIG. 4'is the rib adjacent the transverse groove 14 and therefore has the highest inclination of all the ribs 20, i.e., the most actue angle 9. By comparing FIG. 4 with FIG. 2, it can be seen that when the saddle is in place the holding pressure exerted by the clamps C will deform that portion of the longitudinal runners extending below said cross ribs to cause greater bite onto the member M to resist shifting, both longitudinally and laterally. The cross ribs adjacent the hinge 16 just contact the surface of the mounting member M and thereby add stability to this area of the saddle 10 where reinforcement has been reduced to a minimum by the presence of the hinge 16.

The runners 21 tend to deform more near the ends whereon the holding forces are applied thereby giving desired greater resiliency to the mounting of the saddle. Deforming of the runners facilitates a more positive seating of said saddle without substantially altering the outer radius of curvature when said saddle is positioned on said mounting member M. Removing the holding forces allows the runners 21 to return to the underformed position.

Thus, it can be concluded from the above discussion that providing a rear surface of the saddle with a ridged or waffle configuration comprising a plurality of transverse ribs 20 and a plurality of longitudinal runners 21 serves to not only minimize the amount of material required in saddle construction thereby reducing saddle weight, but also is effective in maintaining requisite saddle strength and in improving positive seating features.

FIG. 3 shows dimensions for the typical saddle l0 fabricated in accordance with the present invention. Thus, when the mounting member M comprises a 15 inch diameter printing cylinder and the printing plate P comprises a 0.065' inch total thickness, the total thickness of plate plus saddle is shown to be 0.4375 inch, i.e., the total thickness comprises the height of the longitudinal runners, thickness of saddle body 11, and

total thickness of the printing plate P. The thickness of saddle body 11 in this example is or may be 0.100 inch. The plate locking means 15, shown in detail in FIGS.

4 and 5, comprises longitudinal runner extensions 26 and locking pins 27, said locking pins being formed on said extensions. Edge 30 of the printing plateP comprises a plurality of apertures 31 adapted to fasten to said locking means, thereby securely locking said print- -ing plate to said handle. Placement of said locking means relative to the printing plate edge 30 is generally shown in FIG. 1. The transverse rib forming shoulder 50 is seen to be triangular shaped with the apex of said triangle affixed to the underside surface 13 of the body 11. The outer face of the shoulder is perpendicularly disposed to said underside surface 13 and forms an abutment for said runner extensions 26. Inside face 41 of the shoulder 50 defines one side of the transverse groove 14. As shown in FIG. 5, clamp C imparts the holding force to said face 41.

Longitudinal runners 21 are cut away to form arcuate face 42 of groove 14 (see FIG. 5), which expedites attachment of the holding clamps C to the saddle. The intersection of faces 41 and 42 forms acute angle 1 Hinge 16 is best shown in FIG. 3. Said hinge comprises a cutout portion, or interruption, of the longitudinal runners 21 forming angled sides 61 and a transverse groove 62 formed in the underside surface 13.

The hinge 16 is located at the middle of saddle 10. The general location of hinge 16 is best shown in FIG. 2.

The resilient nature of the plastic material forming the saddle combined with the groove 62 causes hinge 16 to be a living hinge so as to facilitate flexing of the saddle when attaching the printing plate P. After the plate has been attached and the saddle released, resulting in application of a tensile force to said printing plate as shown in dotted line outline of FIG. 1, wrinkling of the plate P prior to or during installation is advantageously prevented.

In operation, as shown in FIG. 1, the plate P is attached to the saddle by flexing said saddle at the hinge 16 into the full line position, laying plate P across the top of the flexed saddle, securing the edges 30 onto the locking means 15, and then releasing the flexing force. Upon releasing the flexing force, the saddle returns to the dashed line or standby position, thereby applying the tensile force to plate P. The tensile force prevents wrinkling of plate P before or during installation and clamp down onto the member M. The high proportional elastic limit of the nylon plastic material which is combined with hinge means 16 in this invention allows the saddle to return to standby position without a permanent set.

In summary of the salient features of the invention, a printing plate saddle has been provided that employs waffle ridging reinforcement on the underneath surface 13 that allows for a lighter weight saddle without sacrificing the strength that is necessary. The longitudinal runners 21 of the reinforcement deform to hold the saddle against movement on the mounting member M. The cross ribs are equal in length and extend at a varying angle 0 to not only provide the draft for easy removal from the forming mold, but to also stabilize the area adjacent the hinge l6 and at the same time provide the resiliency needed adjacent the ends. The living hinge l6 eliminates loose parts associated with mechanical pin type hinges and provides natural resiliency to draw the plate P tight while in the standby position to prevent damage plate P.

In this disclosure, there is shown and described only to the thin-shell the preferred embodiment of the invention, but, as

voluntary return of said saddle without permanently deforming the same, reinforcement ridging on the underside of said body, said ridging including at least a plurality of curved longitudinal runners and a plurality of cross ribs, said hinge means being formed by a notch through said longitudinal runners at approximately the center of said saddle, saidridging being resilient and minimizing both the weight of said saddle and the total area of engagement between the saddle and the mounting member, the overall height of said cross ribs in the direction normal to said mounting surface being less than said runners, said longitudinal runners providing the only substantial engagement with said mounting member thereby allowing undiminished application of said holding pressure to said mounting member thereby retaining overall structural strength of said saddle while enhancing the effect of holding forces used in affixing said saddle to said mounting member.

2. The saddle in claim 1 wherein said saddle is formed of a lightweight plastic material thereby providing the saddle with strength and resiliency which will resist clamping forces and prevent fatigue weakening during extended use of said saddle.

3. The saddle of claim 1 including a varying angle of said ribs from substantially perpendicular adjacent said hinge to an acute angle adjacent the ends of said saddle, said angular variation providing increased resilience and tighter adherence to said mounting member while providing a draft means which facilitates withdrawing said saddle from a forming mold.

4. The saddle of claim 1 wherein said cross ribs are substantially equal in length, the cross ribs adjacent said hinge means contacting said mounting member to provide stability and the cross ribs adjacent the ends being spaced therefrom to provide increased resiliency.

5. The saddle of claim 3 wherein the variation of said angle is progressive from the hinge toward the ends.

6. The saddle of claim 1 wherein said runners include extensions, said extensions containing locking means for conveniently affixing said printing plate to said saddle.

7. The saddle of claim 6 including a transverse groove locate between said longitudinal runners and said extensions at each end of said saddle, said groove serving to conveniently allow clamping said saddle to said mounting member.

. 8. The saddle of claim 1 wherein said hinge is located adjacent the midpoint of said saddle and being formed by removal of a portion of said longitudinal ribs and a coextensive centrally located tranverse groove on the underside of said saddle, said hinge providing a capability of deformation of said printing plate prior to or during installation onto said mounting member.

* t i 1 I 

1. A saddle for mounting thin-shell printing plates onto a curved mounting member comprising a curved body, a substantially smooth top face providing a surface for the mounting of said printing plate, a resilient hinge means across said saddle to permit flexing and voluntary return of said saddle without permanently deforming the same, reinforcement ridging on the underside of said body, said ridging including at least a plurality of curved longitudinal runners and a plurality of cross ribs, said hinge means being formed by a notch through said longitudinal runners at approximately the center of said saddle, said ridging being resilient and minimizing both the weight of said saddle and the total area of engagement between the saddle and the mounting member, the overall height of said cross ribs in the direction normal to said mounting surface being less than said runners, said longitudinal runners providing the only substantial engagement with said mounting member thereby allowing undiminished application of said holding pressure to said mounting member thereby retaining overall structural strength of said saddle while enhancing the effect of holding forces used in affixing said saddle to said mounting member.
 2. The saddle in claim 1 wherein said saddle is formed of a lightweight plastic material thereby providing the saddle with strength and resiliency which will resist clamping forces and prevent fatigue weakening during extended use of said saddle.
 3. The saddle of claim 1 including a varying angle of said ribs from substantially perpendicular adjacent said hinge to an acute angle adjacent the ends of said saddle, said angular variation providing increased resilience and tighter adherence to said mounting member while providing a draft means which facilitates withdrawing said saddle from a forming mold.
 4. The saddle of claim 1 wherein said cross ribs are substantially equal in length, the cross ribs adjacent said hinge means contacting said mounting member to provide stability and the cross ribs adjacent the ends being spaced therefrom to provide increased resiliency.
 5. The saddle of claim 3 wherein the variation of said angle is progressive from the hinge toward the ends.
 6. The saddle of claim 1 wherein said runners include extensions, said extensions containing locking meanS for conveniently affixing said printing plate to said saddle.
 7. The saddle of claim 6 including a transverse groove locate between said longitudinal runners and said extensions at each end of said saddle, said groove serving to conveniently allow clamping said saddle to said mounting member.
 8. The saddle of claim 1 wherein said hinge is located adjacent the midpoint of said saddle and being formed by removal of a portion of said longitudinal ribs and a coextensive centrally located tranverse groove on the underside of said saddle, said hinge providing a capability of deformation of said printing plate prior to or during installation onto said mounting member. 